In collapsible canopy frames having side poles and edge scissor assemblies that interconnect the side poles, side poles are often telescopically extendable. For example, each telescoping side pole has an upper section and a lower section that are slidably coupled to one another. This way, the size of the canopy frame in the collapsed state can be reduced. To maintain the side pole in an extended position, a locking mechanism is typically used. Locking mechanisms are also used to lock sliding mounting brackets pivotably coupled to lower outer ends of the edge scissor assemblies to the side pole such that the edge scissor assemblies can be fixed in an extended position when the canopy frame has been opened.
Pull pin assemblies are typically used as the locking mechanism in the collapsible canopies. Such pull pin assemblies have a pulling member such as a ring attached to the head of the pin. The locking mechanism is disengaged by pulling such pulling member. However, such pulling mechanism is often cumbersome to use in that the user holds the side pole with one hand while pulling the pulling member with the other. Therefore, there is a need for a locking mechanism for height adjustment as well as for fixing the sliding mounting bracket to the side pole that can be operate using one hand.